PROS: It dissolves in water and lowers the freezing point of water so a lower temperature is required for ice to form. This makes the road less treacherous for vehicles. Road salt is usually cheap and readily available. Since salt is already a constituent of sea water, it does not cause pollution when washed away.
CONS: Salt dissolved in water is corrosive to metal. A metalled road surface may eventually be attacked by the corrosive, leading to damage of the surface. The salt solution is splashed on to the bodies and into the engine parts of vehicles and, unless properly protected, the metal parts of the vehicle will become corroded. Salt solution is a good conductor of electricity so it could under certain circumstances affect the electrical circuits within vehicles. When the salt solution dries out it leaves a deposit of white salt on the surface. The spreading of road salt is often carried out by specially equipped vehicles, so there is a cost incurred in salt spreading. Usually salt is mixed with grit.
Question-
Which seismic waves are felt first at a seismic station
Answer-
Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.
There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are body waves and surface waves. Body waves can travel through the earth's inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.
BODY WAVES
Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves.
P WAVES
The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to 'arrive' at a seismic station. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. It pushes and pulls the rock it moves through just like sound waves push and pull the air. Have you ever heard a big clap of thunder and heard the windows rattle at the same time? The windows rattle because the sound waves were pushing and pulling on the window glass much like P waves push and pull on rock. Sometimes animals can hear the P waves of an earthquake. Dogs, for instance, commonly begin barking hysterically just before an earthquake 'hits' (or more specifically, before the surface waves arrive). Usually people can only feel the bump and rattle of these waves.
P waves are also known as compressional waves, because of the pushing and pulling they do. Subjected to a P wave, particles move in the same direction that the the wave is moving in, which is the direction that the energy is traveling in, and is sometimes called the 'direction of wave propagation'. Click here to see a P wave in action.
Answer:
The elbow may flex or probate from its current anatomical position
Out of the following given choices;
15
7
24
95
The answer is 95%. The biggest contributors of this percentage are developing countries that do not have proper waste disposal mechanisms such as well structured sewer systems. It is estimated that 70% of industrial wastes in developing countries are disposed off untreated into waters where they end up in oceans through rain wash.
